Plastic bituminous compositions



with asphalt paints,

Patented May-22, 1945 PLASTIC BITUMINOUS CQMPOSH'IONS James B. Mullin,San Marino, Calif.

No Drawing. Application Serial No.

2 Claims. 10627 7) The instant application is a continuation as tocommon subject matter of my copending application entitled "Plasticbituminous compositions,

filed by me on January 30, 1940, under Serial No.

Compositions of the character about to be described find considerableuse in industry for applying waterprooflng coatings 'in situations inwhich the thickest layer producible by painting nous emulsions islnsuflicient. used for patching roofs, drains and, on a larger scale,for waterproofing brick or concrete walls in the like and for protectinginsulating coverings exposed to the weather.

Thus, they are molten asphalts or bitumi-- cellars, reservoirs andsealing fiashings and I For such purposes the co position is usuallyapplied with a trowel or float and it is essential to proper workabilitythat it have a buttery or salve-like consistency, free from stringiness,tack- 'iness or adherence to the trowel, and also that it be free fromany tendency applied to vertical or steeply It is has set to run orcrawl when inclined surfaces.

soften, granulate or scale when subjected to the action of the elementsor of standing water. For most uses it is also essential that thecoating, after hardening, be waterproof in the sense of beingimpermeable to water.

Such products, known commercially but somewhat inaccurately asbituminous mastics, have consisted heretofore of more or lessfluidbitumens or bituminous emulsions brought to a pasty consistency byloading with finely divided solids.

In the older practice, a reduced coal tar or semiliquid asphalt wasmixed, while hot, with a large proportion of some finely divided, inertsolid such as talc, kaolin or sugar-house lime. These products weresatisfactorily water-resistant and waterproof but were too'sticky totrowel readily and could not be applied in thick layers on other thanhorizontal surfaces because of their tendency to crawl, during theextended hardening p riod.

.In more modern practice, a liquid bituminous emulsion is first formed,ordinarily with the use of clay or other line solid asthe emulsifyingagent, this emulsion being then loaded to the desired consistency withfurther quantities of clay or an equivalent solid in a state or extremesubdivision.

This practice has the advantage over its prealso essential that thecoating, after it and hardened, be free from water-soluble substancesand from any tendency to emulsify,

May 17, 1943. 487,385

decessor that a much harder bitumen may be used and that the stringinessof the earlier compositions may be considerably reduced. On the otherhand, the applied coating, after hardening,

tends to lose its lustre and acquire a brownish tinge. It is also likelynot to be impervious to water and tends strongly to degenerate (by slowre-emulsification) under the, action of water and the elements. Further.these compositions are tedious and costly to manufacture and. unlessprepared with the greatest care, are likely to separate out part of themineral ingredients in continued storage.

For various reasons, the ideal plastic bituminous composition is onewhich consists substantially solely of bitumen emulsified with water.

Such emulsions, however, are naturallyof a liquid consistency because ofthe continuity of the aqueous phase. The viscosity ofthese liquidemulsions can be increased, within narrow limits, by increasing theproportion of bitumen, but the desired buttery consistency is notthereby attained,

the consistency being that of a viscous liquid such as molasses.Inversion of the emulsion, making the bitumen the continuous phase,completely destroys workability. Thus, so far as I am aware,

the problem of imparting a satisfactory working consistency to a fluidbituminous emulsion has not heretofore been solved.

I have discovered that a'plas'tic compositionhaving the idealconsistency for spreading, free from tendency to run or crawl eitherbefore or after setting, waterproof after hardening and highly resistant'to water and to the action of the elements, may be produced by thecarefully controlled precipitation of certain colloids in the aqueousphase of a thinly fluid bituminous emulsion of the type formed by theaction of alkali on a saponiilable substance present in or added to thebitumen; i. e., of the type which avoids the use of solids asemulsifying agents.

In putting the invention into practice I start {with a conventionalliquid bituminous emulsion of either the penetrating or the mixing type.

This emulsion may be prepared either from an asphalt capable ofemulsifying with an alkali solution alone (an asphalt containingnaphthenic or the so-called "aspha1togenic acids) or one incapable of soemulsifying; The initial consistency of this asphalt may be governed tosuit the purpose to which the plastic composition is to be applied, andmay range from a thickly fluid to a moderately hard consistency. Theupper limit oi fine, tumen, as for example wort, quillai,

2 hardness is fixed by the requirement that the dispersed asphaltparticles'must coalesce to form a dense and impermeable layer as theaqueous phase disappears. In the use of a naturally emulsifiable asphaltI prefer to use from 50 to 65 parts by weight of the. bitumen with from50 to 35 parts by weight of a dilute alkali solution. contain from 0.1%to 2% by weight of any alkali metal hydroxide or carbonate, such forexample as sodium or potassium hydroxide, sodium or potassium carbonate,or proportionatequantities of the alkali silicates. or the trialkylphosphates. The bitumen being brought to a temperature of fluidity,emulsification is effected by any conventional means such as mechanicalagitation or pump circulation.

The proportions of. itumen and of aqueous alkali are suggestive only.Ordinarily it would not be desirable to use less than 50% men, but insome cases it would be permissible to use more than 65%. In anycase theuse of a thickly fluid, viscous emulsion as a starting ma terial must beavoided in order to obtain a satisfactory product. The nature of thebitumen used will have some influence on the maximum proportion ofbitumen which the emulsion will tolerate.

If a nonemulsifiable asphalt is taken as the starting material, anaddition of a very minute amount of soap should be made, preferably byadding oleic acid to the alkali solution before starting to emulsify.The quantity of soap shouldbe such as to permit the formation of aintimateand stable dispersionof the bifrom a mere trace, of the of bitu-This solution may order of 0.01% of the total weight of materials,

up to 0.5%. The quantity as low as possible as it is undesirabl tointroduce water-soluble materials into the final coating, and the use ofthe large proportions of soap disclosed in some of the earlier emulsionpatents should be avoided.

To the finished liquid em small quantity of an organic stabilizingcolloid. For this purpose I' prefer to use casein when available, thoughnumerous other colloids may be used in its'stead. For example, I may usealbumin, glue or gelatine, starch, the roots or root barks havingcolloidal constituents such as soapquebracho, lilywort, licorice orsoaproot, or other colloid-containing substances such as blood, milk,etc. and other inorganic colloids are nonfunctional for my purpose,though their presence in small quantities does not interfere with thegelatinization if the organic colloidal substance also be added. Some ofthe roots and root barks contain important quantities of. tannin, but asthe thickening or gelatinization about to bedescribed is produced by theuse of numerous substances which are wholly free from tannin it appearsthat the presence of this constituent is incidental and immaterial. Sofar as I am aware, all of the organic substances having well developedcolloidal properties and stabilizing properties for bituminous emulsionsmay be utilized. It will be pointed out, however, that not all of thecolloids are of equal value for my purpose and that in the use of someof them a closer selection of the precipitating agent must be made' thanwhen other colloids are used.

The colloid may be introduced into the emulsion in one of a variety ofways, according to its physical character and the readiness with whichlsion I then add a- The clays, bentonites of soap should be held I Forexample, the roots and root barks may be ground very finely, either wetor dry, and made into a thin paste or slurry with water, this paste thenbeing disseminated through the emulsion by gentle stirring. Casein. maysimilarly be added but without previous grinding. The glues, gelatins,starches and dry albumins should be thoroughly soaked and swelled inwater and, preferably, gently heated before adding to the emulsion. Orthe last named substances may be added in the same manner as casein, thepaste being stirred through the emulsion, the whole allowed to stand forsome hours and a gentle heat then applied. Some economy of colloid maybe effected in-this manner though considerably more time is required.The aim in any case is to disseminate the colloid evenly throughout theaqueous phase of the emulsion, and the technique followed willnecessarily be governed by the nature of the colloid used.

The final step in the preparation of the plastic composition is tointermix with the colloid-con taining emulsion the critical quantity ofa gelatinizing agent which is compatible with the specific colloid used.The methods of predetermining compatibility and critical dosage will bedescribed below, atinizing agents from which the selection may be made.For the present it may be assumed that these factors-are known. 7

The gelatinizing agent,'which will be either a salt or an acid, may beadded either as a strong aqueous solution or, in the case of som salts,

it disperses.

as a dry powder. If the substance be soluble in "a small quantity ofwater I prefer to bring it to the condition of a substantially saturatedaqueous solution. If the gelatinizing agent be less readily soluble, sothat the quantity of water required to bring it into aqueous solutionwould materially 40 dilute the final product, I add it in the form ofsolution and is therefore more gradual.

a dry powder or of an aqueous suspension of such powder and'allow timefor it to dissolve in the water of the emulsion. Strong acids such assulfuric or nitric should be diluted to the point at which any secondaryreaction on the bitumen itself will be avoided.

On the addition to the colloid-containing emulsion of the criticalquantity of gelatinizing agent which is compatible with the particularcolloid used, the emulsion thickens and assumes the described-buttery orsalve-like consistency as soon as the agent has been diffused throughoutthe emulsion. In this consistency, the product is short and devoidof-stringiness, spreads readily and smoothly without adhering to orfollowing the trowel, and flows only under pressure.

'This result is produced instantaneously in adding and intermixingaqueous solutions of the agent. If the latter be in the form of anaqueous suspension of a slowly soluble powder the change of state willnot occur until the agent passes into When the product is finished andin packages for shipment.

the change occurs may be used or placed -It should be protected fromtheair when in storage, to avoid change of consistency due to loss of waterby evaporation.

A great number of both salts and acids may be used as gelatinizingagents with appropriate colloids. Not all of the salts nor all of theacids are functional, and some acids which give a satisfactory resultwith some colloids are nonfunctional with others. Results obtainedexperimentally in the use of various salts, alkalis and acids as well asthe range of gell t can? with dlflerent colloids are set forth in thetable motels ore nonfunction'o for the preparation of following: r i myplastic composition.

Golatinizing agent Colloid 2 3; w Oliotooter of product 0. 60 '0. 361First usiity lactic. :50 0. 472 13%. p 1.00 0. e25 Do. it", tlt s" 0. i1.00 0,371 Do. 2. 00 0. 3.38 Do. 2. 50 0; 379 Do. 0. 50 0. 796 D0. 1. 000.433 Do. Antimony tnchloride 0. 60 1:430 Do. Cadmium nitrate 0. 50 0.770 Do. Chromium trichlorlde. 3g (1,. all? go. 0. Cobaltic chloride g 0."mmde 1. as 0. 112 Do. u. so e one Do. 0. 60 0.780 Do. I. 33 1. 084 Do.Cupric sulfate d l. 20 0. 390 Do. B1 0. 50 0. 682 Do. 2 00 0. 488 Do. 0.50 1. 131 Do. 0. 60 0. 250 D0. 0. 60 l. 710 D0. as as s o. Nickelnitrate f 23 1 2: g o. l 1. as 1 2:; go. 0. Stumic chloride 23 g 2% guse o. 1. g g. 3% 1130. o. o. i i 3.23 E no, hmk

use 11 mu non 0 none. Barium chloride 1. 33 4. 000 Fair grade plastic,Sodium chloride 3. no 8. 000 Do. Ammonium chloride 6. 00 10. '400 Do.Potassium hydroxide 0. 50 Excess Viscous, not plastic. Sodium carbonateo. 50 Excess Do. 0. 50 0. 270 First quality plastic.

3'28 as s o. Hydrochloric acid u B 50 0.324 In 2.00 Excess Product notobtained. 0. 50. Excess Do. Nitric acld Cssei 0. 60, 0. 3&6 Firstquality plastic. 0. 60 0. 356 D0. 0. b0 0. 400 Do. o 1.00 0.380 Do.Phosphoric acid (ortho) mm 3% 3; l. 00 0. 190 D0.

2.00 Excess Product not obtained. 8'? S 3 5; m 1: m is u 1'3 (1118 S 0.u c. w L 33 288 y p Omiic acid 0. 50 0. 388 Do. 0150 1.166 Do. 0. 50 1t4121] D0. 1. as 0. 625 Do. Acetic acid ...d0 1. 1. 264) Do. 0. 0. 400Do. 2.00 Excess Product not obtained. 0. 50 Excess Do. Boric acid .11.00 Excess D0.

which I drew from work are as follows: lts equivalents, blood desirablecolloids for The general conclusions this and other experimental 1.Casein, quebrecho and and albumin are the most my purpose and arefunctional with ell of the soluble heavy metal salts, with some of thealkaliearth, metal salts and with the stronger acids;

2. starch and gelatine are functional with the heavy metal salts but donot give desirable results with the acids;

I 3, The salts of the smell-earth motels are functions] with some 01'the colloids but may be considered on. the border line;

The salts of the alkali metals are functional with casein, at least, butrequire such extravagant doses as to be of no utility for my purpose;

5. The acids are less desirable as gelatinizing agents than the heavymetal salts, because of the acidity of the products obtained, though thestronger acids are functional with the more de- 'sireble colloids.

a; The hydroxides a carbonates or the alkali 7. The hydrogen ionconcentration oi the product may very over to wide muse, from pH Lil topH 9.11 in verious experhnentsens sppeers to have no relation whateverto the formetion of the product or to its cherccterlstics when fo 'med.

As these generalities do not eifiord any dependable guide to theselection of meteriels which will certainly be functional incombination, I have sought for and have discovesed c. test by which thecompatibility oi the preferred or ayelleble colloid with ves'iousselstmizing agents may be predetemined.

In making. this test I prepares dispersion of about 2% by weight of theselected colloid in. e 1 aqueous solution of sodium carbonate. Into thisdispersion I feed slowly, with stirring, a. total of about 40% by volumeof the strong aqueous to be tested. If; during this addition, aprecipitate appears, the colloid and the agent are compatible and itthis comblnationroi additives is used in a. suitable emullion and in thecritical proportion the desired a not be confused with a precipitate.

plastic composition will be obtained. Per contra, if no precipitate isformed the combination is nonfunctional, though each of the materialsused may be functional with another agent or with another colloid. Inusing an acid as the agent there may be an evolution of carbon dioxidefrom the sodium carbonate, which should The precipitate may be flaky,granular, powdery or gelatinous in various combinations, and in somecases may partially redissolve before all of the agent has been added.None of these factors appears to be'material to the interpretation ofthe test.

There is no dependable relation between the quantity of an agentrequired to precipitate a given colloid from aqueous dispersion and thequantity of the same agent required to produce the plastic compositionwhen added to an emulsion containing the same colloid. The test isconsidered to be qualitative only, for determining compatibility, i. e.,functionality of the combination. The dosage of the agent is determinedin a second test which will later be described.

The dosages indicated in the table above are suggestive but notlimiting. With each different colloid there is some minimum dosebelowwhich the. emulsion breaks instead of assuming the plastic state onthe addition of the acid or salt. With casein, blood and gelatine theminimum dose of colloid appears to be about 0.25% of the weight ofemulsion treated; with quebracho and other roots and root barks about0.50% and with starch about 1.00%. The maximum dosage is not so limitedand an excess of the colloid appearsto be harmless so far as theconsistency and stability of the product are concerned. However, thecolloid is an important element in the final cost of the product andfurther it is undesirable to have any excess of organic matter presentin the applied coating, as tending to reduce weather resistance.

As it is impossible to lay down an absolute rule as to optimum dosage ofcolloid, by reason of the variation in intrinsic stability of differentemulsions in which it may be used, I consider it desirable to useinitially about the quantity indicated by the above'table and graduallyto reduce the dosage as experience or laboratory experiment may indicateas being safe.

Having prepared a suitable thinly fluid emulsion as above described, andhaving dispersed in a sample of this emulsion a known dose of thepreferred or available colloid, and having determined in the mannerabove referred to that the intended gelatinizing agent is'actuallyfunctional with the specific colloid used, the final preliminary step isto determine the critical dosage of the agent, salt or acid, by whichthe plastic consistency is produced.

This test is a simple titration, at room temperature, of a measured orweighed quantity of the colloid-containing emulsion with the solution ofagent intended for large scale use.

As the solution is added to the emulsion, slowly and with gentlestirring, local coagulation takes place and, as this coagulation isstirred out, the emulsion will be observed to thicken and gradually tobecome short, i. e., salve-like rather than thickly viscous. Theaddition of an excess of the gelatinizing agent may result merely in thethinning of the plastic, buttery product,

or itmay first produc'e a change from the salvelike consistency to thethickly fluid consistency and thereafter reduce the viscosity of theprodnot. The critical point is that at which the change of state isreadily observed experimentally, and is ordinarily so abrupt that intitrating samples of 25 m1. of the emulsion a single drop of thesolution will produce the change, thus affording a quite definite endpoint for the titration.

In preparing a commercial batch'of the composition the relativequantities of emulsion and gelatinizing agent may be taken directly fromthe laboratory result.- It is desirable, however, as the end of the doseof agent is approached, to add the solution slowly and cautiously and tonote the change in appearance of the batch. In case a batch isaccidentally overdosed with the agent and the point of maximumconsistency thus passed, the desired consistency may be restored bycautious additions of emulsion containing its normal quota of thecolloid.

This restoration of an overdosed batch should not be attempted by addingfurther colloid to the batch. Strangely enough, the dose of gelatinizingagent appears, in some cases at least, to decrease as the dose ofcolloid is increased. The following experimental figures a series oftests in which substantially the same consistency of composition wasrealized in each case.

It is possible, by suitable selection of colloid and of gelatinizingagent, to obtain a product which is substantially neutral or, forspecial purposes, a product distinctly acid or alkaline as may bepreferred. Thus, casein gives a product within the range pH 6.0 to pH7.9 with salts of copper, silver, cadmium, zinc, lead, aluminum,manganese and nickel. 8.0 and above with free acids and the chlorides oftin, chromium yield acid products, from pH 5.5 down Quebracho yieldsproducts of v to pH 1.8, with both of these colloids. In theseexperiments the pH of the original emulsion was and after addition ofthe quebracho 10.6.

Plastic bituminous compositions produced by the methods described abovehave all the desirable characteristics developed to the highest degree.They havethe required buttery consistency, spread easily and maintaintheir position even when spread in layers of considerable thickness onsteeply inclined surfaces. The aqueous phase rapidly disappears and thecoating remaining is dense, impervious to water and highly resistant tothe elements. Thecomposition is stable in storage over long periods andits consist-., ency is not altered by stirring. It will tolerate and, byreason of its consistency, will dependably support even a considerableaddition of solid from fluid to plastic is observed. This change ofstate is difficult to describe but are illustrative, referring to v mostof the above salts. The

antimony and after addition of casein the pH was 10.1 v

tuted for the organic colloid salts of rather than to the finishedplastic composition.

For example, asbestos fibre maybe brought to a thickly fluent conditionby stirring with .water and this aqueous mass dispersed in the liquidemiil sion, the colloidal constituent being added to the emulsionpreviously or simultaneously as may be preferred. The whole being wellblended, the gelatinizing agent is added and stirred in, the change inconsistency occurring during this step. The finished product containingfibrous material has the characteristic buttery consistency, somewhatmodified by the presence of the flbres, and should be of suchconsistency that a rather stifl' brush may be plunged into it forpainting or such that it may be trowelled into place. Such consistenciesare included in the term salve-like" as used in the claims.

in no case is a clay or bentonite to be substiand ordinarily it is notdesirable to add clays or composition. The single exception is that thesmoothness of free trowelllng characteristic may in some cases beimproved by the addition of a minute quantity, of the order of l byweight, of a highly colloidal bentonitic clay. V

The acids hereinabove described as operative have dissociation constantsfor the first hydrogengreater thanlX 10*, and that limitation is fixedin the appended claims to exclude certain weai: acids, such as boricacid, which are. inoperative. 'I'hesalts herein disclosed as-operatlveare than +2.4, and that limitation is fixed in the claims to excludesalts of the alkali and alkalineearth metals which are nonfunctional orare functional to so slight a degree as to be useless for the presentpurpose.

I claim as my invention:

1. A plastic bituminous composition: a nonflubentonites to the as theemulsifying agent, in such proportions as normally to produce a thinlyfluid emulsion, said mass containing small proportions of additivesincluding a selected organic, colloidal, stabilizing substance and awater-soluble solidifying agent selected from the group consisting ofthe acids having a dissociation constant for the first hy-' drogengreater than l 10-' and the water-solumetals having electrode potentialsless containing substantially all the water ble salts of metals havingan electrode potential at 25' cent. lower than +2.4, said solidifyingagent having the further property of precipitating said selected colloidfrom dispersion in emulsion-free alkaline water, the quantity of saidorganic colloidal stabilizing substance being'suflicient to prevent thebreaking oi the-emulsion upon the addition of the solidifying agent, andthe quantity of said solidifying agent being suflicient only to causethe substantial solidification of said thinly fluid emulsion; saidcomposition when finished presentin the original thinly fluid emulsion.

2. The method of producing a plastic bituminous composition having asalve-like texture, free from tackiness and stringiness, and anonfluent, soft, solid consistency, which comprises: preparing a thinlyfluid emulsion of bitumen in water usinglan alkali-metal soap as theemulsifying agent; stabilizing said emulsion by adding thereto' aselected organic, colloidal, stabilizing substance in sufficientquantity to prevent breaking of the emulsion upon the ensuing-additionof a solidifying agent; substantially solidifying said stabilizedemulsion by adding thereto a watersoluble solidifying agent selectedfrom the group consisting of the acids having dissociation constants forthe first hydrogen greater than l X 10" and the water-soluble salts ofmetals having an electrode potential lower than +2.4, said watersolublesolidifying agent having the further property of precipitating saidselected colloid from dispersion in emulsion-free alkaline water;limiting the addition of said agent to the quantity required to effectsaid substantial solidification, and retaining in the finishedcomposition substantiab ly all the water present in the original thinlyfluid emulsion.

JAMES B. MUTLLIN.

